This invention relates in general to the field of modular electronic systems and, more particularly, to a card shelf fire suppression system and method.
Modular electronic systems are generally configured as card shelf assemblies to optimize space efficiency within a central office or other similar facilities. Card shelves include individual plug-in electronic module cards having different functions that communicate across a backplane. The electronic cards may have different thicknesses depending upon the amount of electronic circuitry contained in each electronic card. The electronic cards may also have flanges on the top or bottom which fit into grooves into the card shelf for sliding the electronic cards into the card shelf and plugging the electronic cards into connectors located in the backplane of the card shelf.
The card shelf may also include an open or perforated top and bottom portion to allow thermal energy generated by the electronic cards during operation to escape the card shelf. The card shelf may also include a fan assembly for directing airflow through the card shelf to dissipate thermal energy generated by the electronic cards during operation.
Known card shelves present certain drawbacks. For example, to maximize space within a card shelf, electronic cards are placed in close proximity to one another. As a result, dissipation of thermal energy generated by the electronic cards during operation may be difficult or inadequate to maintain proper operation of the electronic cards. Additionally, the thermal energy generated by the electronic cards may cause a fire to ignite within the card shelf, thereby damaging one or more of the electronic cards. Including fan assemblies in known card shelves also presents certain drawbacks. For example, airflow generated by the fan assembly may cause acceleration and/or propagation of a fire ignited within the card shelf.
The present invention provides a card shelf fire suppression system and method that addresses shortcomings of prior systems and methods. In particular, a passively activated damper system is provided that substantially suppresses a fire that may ignite within the card shelf.
According to one embodiment of the present invention, a card shelf includes a backplane and a plurality of slots each configured to receive an electronic card adapted for engagement with the backplane. The system also includes an airflow path for providing airflow adjacent the electronic card for dissipating thermal energy generated by the electronic card. The system further includes a damper system disposed proximate the slots and operable to passively activate in response to a predetermined temperature condition to substantially prevent airflow through the slots.
According to another embodiment of the present invention, a method for passively controlling airflow to an electronic card in a card shelf includes providing a damper disposed proximate the electronic card. The damper includes a thermal fuse being responsive to a predetermined temperature condition. The method also includes supporting the damper proximate the thermal fuse in a first position relative to the electronic card such that airflow passes adjacent the electronic card. The method further includes passively activating the damper in response to the predetermined temperature condition such that the thermal fuse deforms to cause the damper to travel from the first position to a second position relative to the electronic card to substantially prevent airflow adjacent the electronic card.
Technical advantages of the present invention include providing an improved method and system for passively suppressing a fire that may ignite within a card shelf. In particular, a damper system is provided to passively activate in response to a predetermined temperature condition. The predetermined temperature condition may be selected such that an elevated temperature condition generally associated with a fire within the card shelf causes passive activation of the damper system. According to one embodiment of the present invention, the damper system includes a thermal fuse coupled to a damper. The damper is supported at the location of the thermal fuse in a position to accommodate airflow through the card shelf during normal operating conditions. In response to an elevated temperature condition that may be indicative of a fire within the card shelf, the thermal fuse deforms, thereby causing the damper to become unsupported and travel to a closed position to substantially prevent airflow adjacent the electronic cards. Thus, the system is passively activated to substantially suppress and/or contain a fire ignited within the card shelf.
Another technical advantage of the present invention includes providing a card shelf fire suppression system and method that is generally inexpensive and less susceptible to electrical and/or mechanical failure. For example, according to one embodiment of the present invention, a damper is supported at a location of a thermal fuse such that deformation of the thermal fuse in response to an elevated temperature condition causes the damper to become unsupported and travel to a closed position, thereby substantially preventing airflow adjacent the electronic card. In this embodiment, gravitational forces act on the damper to move the damper from an open position to the closed position. Thus, the present invention is less susceptible to electrical and/or mechanical failure that may be associated with electrically-actuated fire damper systems.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions and claims.